Cyclostratigraphy of a Tithonian-Valanginian carbonate ramp succession, Southern Mendoza, Argentina: Implications for the Jurassic-Cretaceous boundary in the Neuquén Basin

D.A. KIETZMANN; PALMA, R.M.

Lisboa

Congreso; !er Congreso Internacional de Estratigrafía; 2013

Detailed sedimentological, sequence stratigraphical and cyclostratigraphical analyses have been made from four sections of the Vaca Muerta Formation. This unit is characterized by a decimetre-scale rhythmic alternation of marls and limestones. It consists of five facies associations, which represent basin to middle carbonate ramp deposits. Rythmic vertical organization shows a well-ordered hierarchy of cycles, where elementary cycles, bundles of cycles and superbundles within the Milankovitch frequency band have been recognized. Cyclostratigraphic data allowed us to build a floating orbital scale for the Lower Tithonian-Lower Valanginian interval in the Neuquén Basin. Orbital calibration of these sections is consistent with Riccardi?s biostratigraphic scheme, wich place de Jurassic-Cretaceous boundary within the Substeueroceras koeneni Ammonite Zone (equivalent to Durangites spp., Jacobi/Grandis and initial Occitanica Standard Zones).